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The October 1971 issue of Esquire Magazine runs an article by Ron Rosenbaum entitled Secrets of the Little Blue Box about Vietnam veteran John T. Draper who discovered that a toy whistle packaged in boxes of Cap'n Crunch cereal could be easily modified to emit a tone at precisely 2600 hertz. This is the same frequency that was used by AT&T long lines to indicate that a trunk line was ready and available to route a new call. |
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